Novel and ff ideas for authors

I just read this particular manwha about a guy who has magic and like all types of magic novels,manwha, and mangas always have that assasin that kills itself via poison so i was wondering isn't there a type of magic about reading the mind of those who dies like the one from that necromancer manwha where he tries to kill his friends who betrayed him cause why do almost all assasins get away with information by eating or drinking poison.